Transparent photocathodes, also called inverted transmission cathodes, are usually produced by building a multi-layer, large area heterostructure on a semiconductor substrate by an epitaxial process. An etch resist layer, an active semi-conductor layer and a protective layer are successively applied from appropriate melts to a substrate in a liquid epitaxial process. After expediently having applied to the protective layer pyrolitically an adhesive coating. this multi-layer wafer is jointed to a carrier, preferably of glass, e.g. by heat treatment in a furnace. Thereafter, parts of the multi-layer wafer, in particular the substrate, are removed completely or partly by etching. The various layer thicknesses are in the order of magnitude of a few .mu.m. The size of the multilayer semiconductor wafer is usually of the same size, or smaller than, the carrier surface to which it is applied. The method used for this purpose is known, e.g. from German OS No. 25 50 056.
As a disadvantage, difficulties were often encountered in contacting the active semiconductor layer and in the appearance of undesirable discharge phenomena during the operation of image intensifier tubes with such a photocathode, irregularities at the photocathode edges having been found as the cause of these difficulties.
The cause of these irregularities obviously was that when etching away especially the substrate after the application of the multi-layer semiconductor wafer to the glass carrier, there were also dissolved, despite the use of maskings at the rim, parts of the active semiconductor layer between the resist layer and the protective layer, with parts of these adjacent layers then crumbling off subsequently. These irregularities impaired bondings, e.g. produced by vacuum metallizing on the one hand, and they caused undesired discharge phenomena on the other.